Front-end loader for prosthetic occluders and methods thereof

ABSTRACT

The invention pertains to a system, and related methods, for the percutaneous transluminal delivery and retrieval of a prosthetic occluder through a front-end loader. The prosthetic occluder may be, for example, an intracardiac occluder for a patent foramen ovale. The system includes, in one embodiment, a front-end loader having a beveled distal end. In another embodiment, the system includes a front-end loader having a chamfered rim at the beveled distal end.

CROSS REFERENCE TO RELATED APPLICATION(S)

This application is a divisional of U.S. application Ser. No.10/667,747, filed Sep. 22, 2003, currently pending, which claims thebenefit under 35 USC §119(e) to U.S. Application Ser. No. 60/412,953,which was filed on Sep. 23, 2002.

TECHNICAL FIELD

The invention generally relates to a system, and related methods, forthe percutaneous transluminal front-end loading delivery and retrievalof devices used to repair cardiac defects. More particularly, theinvention relates to an improved front-end loader device.

BACKGROUND INFORMATION

Prosthetic occluders for repairing intracardiac defects, such asinteratrial and interventricular septal shunts, patent ductusarteriosus, patent foramen ovale, and occlusion of the left atrialappendage, are well known in the art. Moreover, systems for percutaneoustransluminal front-end loading delivery and retrieval of a prostheticoccluder have been described. Representative is “System for thePercutaneous Transluminal Front-End Loading Delivery of a ProstheticOccluder”, U.S. Pat. No. 5,486,193 (Bourne et al.), the entirety ofwhich is expressly incorporated by reference herein, which discloses acomplete system including a front-end loading portion, a controlassembly, and an introducer.

Significant problems exist, however, with the front-end loaderscurrently known in the art. A first problem that may arise with currentfront-end loaders is the introduction of air into the indwellingintroducer sheath when the front-end loader is introduced into the hubof the introducer sheath to deliver or retrieve a prosthetic occluder.Air that is introduced into a closed system, such as the introducersheaths known in the art, may find its way into the patient'scardiovascular system, risking acute pulmonary embolism, myocardialinfarction, stroke, and possibly death.

A second problem with current front-end loaders is that they are notwell suited, should the need arise, for the retrieval of a prostheticoccluder from the heart or a vessel. Occasionally during a procedure toimplant a prosthetic occluder in a patient, the occluder is an improperfit, deploys improperly, or is in some way damaged and must be retrievedfrom the patient. With current front-end loaders, significant problemsoften arise in attempting to collapse and withdraw the prostheticoccluder from the lumen of the introducer sheath into the lumen of thefront-end loader. For instance, in withdrawing the prosthetic occluderfrom the lumen of the introducer sheath into the lumen of the front-endloader, the proximal portion of the prosthetic occluder may catch on thedistal end of the front-end loader, potentially preventing removal ofthe occluder. For example, the prosthetic occluder may become snagged onthe distal end of the front-end loader, necessitating the removal of theintroducer sheath and the front-end loader from the patient in order toremove the occluder. In essence, the prior art lacks a reliable andefficient system for ensuring that the occluder can be withdrawn intothe front-end loader so that the introducer sheath will not have to beremoved from the patient.

It is, therefore, an object of the present invention to provide afront-end loader that minimizes or eliminates the introduction of airinto an indwelling introducer sheath and that facilitates the retrievalof a prosthetic occluder without removal of the indwelling introducersheath, should the need to do so arise.

SUMMARY OF THE INVENTION

The invention provides a system, and related methods, for thepercutaneous transluminal front-end loading delivery and retrieval of aprosthetic occluder to and from, respectively, a patient's heart.

In accordance with the invention, a percutaneous transluminal system fora prosthetic occluder, and related methods, use a front-end loaderdevice comprising a tube to deliver or retrieve prosthetic occluders.The tube of the front-end loader is beveled at its distal end. When thefront-end loader is introduced into the hub of an indwelling introducersheath, the beveled end serves to minimize or eliminate the introductionof air into the introducer sheath. Additionally, the beveled distal endof the tube of the front-end loader is chamfered, either partly orentirely, around its rim. The chamfered rim facilitates the removal of aprosthetic occluder from the patient's body, should the need to do soarise.

In one aspect, the invention includes a percutaneous transluminal systemfor a prosthetic occluder, including a front-end loader. The front-endloader has a proximal portion that includes an expanded lumen, and adistal portion that includes a tube. The tube has a proximal end, adistal end, and a lumen that extends from the proximal end to the distalend. The distal end of the tube is beveled to font' a beveled end. Thebeveled end receives the prosthetic occluder.

In various embodiments of this aspect of the invention, the beveled endmay be chamfered. The chamfering may occur partially or, alternatively,entirely around the perimeter of the distal end of the tube. In anotherembodiment, the expanded lumen of the proximal portion of the front-endloader may be tapered. Moreover, the expanded tapered lumen may beconically shaped. In an additional embodiment, the beveled end receivesthe prosthetic occluder to withdraw it from a patient's body or thebeveled end receives the prosthetic occluder to deliver it into thepatient's body. For example, the beveled end receives the prostheticoccluder through the distal end of the tube. The prosthetic occluder maybe an intracardiac occluder used to treat, for example, an atrial septaldefect, a ventricular septal defect, patent ductus arteriosus, patentforamen ovale, or occlusion of the left atrial appendage.

In another aspect, the invention includes a percutaneous transluminalsystem for a prosthetic occluder, including a front-end loader. Thefront-end loader has a proximal portion that includes an expanded lumen,and a distal portion that includes a tube. The tube has a proximal end,a distal end, a lumen that extends from the proximal end to the distalend, and a chamfered rim. The chamfered rim is positioned at the distalend of the tube, which receives the prosthetic occluder.

In various embodiments of this aspect of the invention, the distal endof the tube is beveled. The chamfered rim may be chamfered partially or,alternatively, entirely around the perimeter of the distal end of thetube. In another embodiment, the expanded lumen of the proximal portionof the front-end loader may be tapered. Moreover, the expanded taperedlumen may be conically shaped. In an additional embodiment, the distalend of the tube receives the prosthetic occluder to withdraw it from apatient's body or the distal end receives the prosthetic occluder todeliver it into the patient's body. For example, the distal end of thetube receives the prosthetic occluder through the distal end. Theprosthetic occluder may be an intracardiac occluder used to treat, forexample, an atrial septal defect, a ventricular septal defect, patentductus arteriosus, patent foramen ovale, or occlusion of the left atrialappendage.

In another aspect, the invention provides a method for delivering acollapsible prosthetic occluder to a patient. The method includes thestep of providing a front-end loader according to the inventiondescribed above. The method further includes the steps of receiving theprosthetic occluder in the lumen of the tube and delivering theprosthetic occluder to the patient. In an embodiment of this aspect ofthe invention, the method may further include the step of introducingthe beveled end of the front-end loader into the lumen of a portion ofan introducer sheath for the prosthetic occluder and crossing a gland.

In yet another aspect, the invention provides a method for retrieving acollapsible prosthetic occluder from a patient. The method includes thestep of providing a front-end loader according to the inventiondescribed above. The method further includes the steps of receiving theprosthetic occluder in the lumen of the tube and retrieving theprosthetic occluder from the patient.

The foregoing and other objects, aspects, features, and advantages ofthe invention will become more apparent from the following descriptionand from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, like reference characters generally refer to the sameparts throughout the different views. Also, the drawings are notnecessarily to scale, emphasis instead generally being placed uponillustrating the principles of the invention.

FIG. 1A is a fragmented plan view of one embodiment of the percutaneoustransluminal front-end loading delivery and retrieval system accordingto the invention.

FIG. 1B is an assembled plan view of the percutaneous transluminalfront-end loading delivery and retrieval system illustrated in FIG. 1A.

FIG. 2 is a cross-sectional view of one embodiment of the front-endloader illustrated in FIG. 1A.

FIG. 3 is a cross-sectional view of another embodiment of the front-endloader illustrated in FIG. 1A.

FIG. 4 is a perspective end view of one embodiment of the distal end ofthe front-end loader illustrated in FIG. 3.

FIG. 5 is a plan view of one embodiment of the distal end of thefront-end loader according to the invention positioned near oneembodiment of the proximal end of the introducer sheath according to theinvention.

FIG. 6 is a plan view of the distal end of the front-end loaderillustrated in FIG. 5 positioned within the lumen of the proximal end ofthe introducer sheath illustrated in FIG. 5.

FIG. 7 is a plan view of the distal end of the front-end loaderillustrated in FIG. 6 further positioned within the lumen of theproximal end of the introducer sheath illustrated in FIG. 6.

FIGS. 8A-8C illustrate the stages, during one embodiment of a retrievalof a prosthetic occluder from a patient, for collapsing the prostheticoccluder in the front-end loader according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention pertains to a system, and related methods, for thepercutaneous transluminal front-end loading delivery and retrieval of aprosthetic occluder. Prosthetic occluders may be used to repaircongenital or acquired defects (shunts) in the heart or the major bloodvessels thereof, including interatrial and interventricular septalshunts, such as a patent foramen ovale, patent ductus arteriosus, andocclusion of the left atrial appendage.

Referring to FIG. 1A, the percutaneous transluminal front-end loadingdelivery and retrieval system 10, according to the invention describedherein, includes a control assembly 14, a front-end loader 12, and anintroducer sheath 150. The control assembly 14, the front-end loader 12,and the introducer sheath 150 are, as shown, separate components.

Referring now to FIG. 1B, when joined together in an assembled state,the control assembly 14 is located at the proximal end 50 of thepercutaneous transluminal front-end loading delivery and retrievalsystem 10, i.e., at the end of the delivery and retrieval system 10 thatis closest to an operator (e.g., a physician). The introducer sheath 150is located at the distal end 52 of the delivery and retrieval system 10and the front-end loader 12 is positioned between the control assembly14 and the introducer sheath 150.

Referring again to FIG. 1A, in one embodiment according to theinvention, the front-end loader 12 has a proximal end 20, a distal end17, and a first lumen 26 proximal to and joined to a second lumen 18.Together, the first lumen 26 and the second lumen 18 extend from theproximal end 20 of the front-end loader 12 to the distal end 17 of thefront-end loader 12. The first lumen 26 is conically shaped and widerthan the second lumen 18. Alternatively, in another embodiment, thefront-end loader 12 includes one lumen. For example, the front-endloader 12 includes but one lumen that narrows from the proximal end 20of the front-end loader 12 to the distal end 17 of the front-end loader12. For its part, the introducer sheath 150 has a proximal end 54, adistal end 56, and a lumen 152 extending from the proximal end 54 to thedistal end 56. The introducer sheath 150 may include, at its proximalend 54, a hub 158.

In general, the introducer sheath 150 is inserted, at its distal end 56,into a patient's body and advanced until the distal end 56 reaches adefect site in the patient's body, such as the heart. In one embodiment,an occluder 200, for example, a septal occluder as described in U.S.Pat. Nos. 5,709,707; 5,425,744; and 5,451,235, is loaded into the firstlumen 26 of the front-end loader 12 at its proximal end 20. Optionally,prior to loading the occluder 200 into the first lumen 26, the operatorcollapses the occluder 200, or a portion thereof. In one embodiment, theoperator collapses the occluder 200, or a portion thereof, by drawingon, for example, sutures attached to the occluder 200. Once placed inthe first lumen 26 of the front-end loader 12, the operator thenadvances the occluder 200 from the conically shaped first lumen 26 tothe narrower second lumen 18, thereby further collapsing the occluder200 into a narrow configuration within the second lumen 18 of thefront-end loader 12 at its distal end 17. Alternatively, in anotherembodiment, the occluder 200 may be loaded directly into the secondlumen 18 of the front-end loader 12 at its distal end 17. Once in thenarrow collapsed configuration, the occluder 200 may be flushed byinfusing an appropriate solution, such as, for example, sterile salineand/or heparin, through the first lumen 26 and the second lumen 28. Suchflushing of the occluder 200 eliminates any air that is trapped withinthe occluder 200 itself. The occluder 200 is then in a suitableconfiguration and state for loading into the lumen 152 of the indwellingintroducer sheath 150 at its proximal end 54. The distal end 17 of thefront-end loader 12, enclosing the occluder 200, is inserted into thelumen 152 of the hub 158 at the proximal end 54 of the previously placedindwelling introducer sheath 150. The control assembly 14 is used toadvance the occluder 200 from the second lumen 18 of the front-endloader 12 into and throughout the lumen 152 of the indwelling introducersheath 150. At the distal end 56 of the indwelling introducer sheath150, which has already been positioned near the defect site in thepatient's body, such as the heart, the occluder 200, through actuationof the control assembly 14, is released and deployed from the lumen 152of the indwelling introducer sheath 150 in a fully expanded openconfiguration.

Referring now to FIG. 2, the front-end loader 12 includes an expandedproximal portion 21 and an elongated distal portion 27. The expandedproximal portion 21 has a proximal end 20, a distal end 19, and a firstlumen 26 extending from the proximal end 20 to the distal end 19. In oneembodiment according to the invention, the expanded proximal portion 21includes a first outer surface 57, a second outer surface 58, a thirdouter surface 60, and a fourth outer surface 62. The first outer surface57 and the fourth outer surface 62 are each substantially similar to theouter surface of a short cylinder. The second outer surface 58 issubstantially similar to the outer surface of a lower portion of a coneand the third outer surface 60 is substantially similar to the outersurface of a longer cylinder. The first outer surface 57 and the fourthouter surface 62 can include any number of threadable engagements 63extending therefrom. The threadable engagements 63 may be used to engagecorresponding receivable threads on the hub 158. In alternativeembodiments, the expanded proximal portion 21 can include any number ofouter surfaces that are substantially similar to any geometrical shape,each with or without any number of threadable engagements 63 extendingtherefrom.

As illustrated in FIG. 2, in one embodiment of the expanded proximalportion 21, the expanded proximal portion 21 includes a first innersurface 64 and a second inner surface 66. The first inner surface 64extends from the proximal end 20 of the expanded proximal portion 21 toan end point 68, which is located proximal to the distal end 19 of theexpanded proximal portion 21. The second inner surface 66 extends fromthe end point 68 to the distal end 19 of the expanded proximal portion21. In the embodiment shown, the first lumen 26 narrows from theproximal end 20 of the expanded proximal portion 21 to the end point 68by tapering. In one embodiment, the first inner surface 64 may be shapedsubstantially similar to the inner surface of a hollow cone.Alternatively, the first inner surface 64 may be shaped substantiallysimilar to the inner surface of a hollow triangular prism.

The end point 68 may be positioned at any point along the long axis ofthe expanded proximal portion 21. In another embodiment of the expandedproximal portion 21, the end point 68 is positioned substantially equalwith the distal end 19 of the expanded proximal portion 21. The expandedproximal portion 21 includes only the first inner surface 64, and notalso the second inner surface 66, and the first lumen 26 narrows fromthe proximal end 20 of the expanded proximal portion 21 all the way tothe distal end 19 of the expanded proximal portion 21 by tapering.Again, the first inner surface 64 may be shaped substantially similar tothe inner surface of a hollow cone. Alternatively, the first innersurface 64 may be shaped substantially similar to the inner surface of ahollow triangular prism.

In yet another embodiment, the expanded proximal portion 21 may includemultiple inner surfaces and the first lumen 26 may narrow from theproximal end 20 to the end point 68, or, alternatively, the distal end19, in a stepwise fashion. The degree by which the first lumen 26narrows may be, but need not be, equal on each step.

Referring still to FIG. 2, in one embodiment of the elongated distalportion 27, the elongated distal portion 27 includes a tube 15 with aproximal end 24, a distal end 17, and a second lumen 18 extending fromthe proximal end 24 to the distal end 17. In the embodiment shown, theproximal end 24 of the tube 15 is positioned substantially equal withthe distal end 19 of the expanded proximal portion 21. In such anembodiment, the tube 15 and the expanded proximal portion 21 form oneintegral component. In another embodiment, the proximal end 24 of thetube 15 is positioned proximal to the distal end 19 of the expandedproximal portion 21, but distal to the end point 68. In such anembodiment, the tube 15 is a separate component from the expandedproximal portion 21. The proximal end 24 of the tube 15 is fitted withinthe lumen 26 of the expanded proximal portion 21 at its distal end 19and is fixed to the second inner surface 66 of the expanded proximalportion 21 by, for example, an adhesive or molten plastic.

hi one embodiment according to the invention, a cross-section of theouter surface 78 of the tube 15, taken at a point between the proximalend 24 and a base 29 of the tube 15, is circular. Alternatively, across-section of the outer surface 78 of the tube 15, taken at a pointin the appropriate aforementioned range, may be shaped like any othergeometrical shape, including, but not limited to, a triangle, a square,a rectangle, a parallelogram, a semi-circle, an ellipse, a wedge, or adiamond.

The second lumen 18 of the tube 15 is narrower than the broadest portion80 of the first lumen 26 of the expanded proximal portion 21. The secondlumen 18 of the tube 15 is sized to compress the occluder 200 (see FIG.1A) to a predetermined cross-sectional area, such that the occluder 200is compatible for insertion into the lumen 152 of the introducer sheath150 at its proximal end 54 (see FIG. 1A).

In one embodiment, a cross-section of the second lumen 18 of the tube15, taken at a point between the proximal end 24 and the base 29 of thetube 15, and/or of the first lumen 26 of the expanded proximal portion21, taken at a point between the end point 68 and the distal end 19 ofthe expanded proximal portion 21, is circular. In alternativeembodiments, a cross-section of the second lumen 18 of the tube 15and/or of the first lumen 26 of the expanded proximal portion 21, eachrespectively taken at a point in the appropriate aforementioned range,may be shaped like any other geometrical shape, including, but notlimited to, a triangle, a square, a rectangle, a parallelogram, asemi-circle, an ellipse, a wedge, or a diamond.

With continued reference to FIG. 2, the distal end 17 of the tube 15 ofthe elongated distal portion 27 of the front-end loader 12 is trimmedtransversely at an angle in the range greater than 0 degrees to about 75degrees, preferably 45 degrees, from a line 40 drawn perpendicular tothe long axis of the tube 15 of the elongated distal portion 27 to forma beveled end 22. The beveled end 22 of the tube 15 of the elongateddistal portion 27 has a tip 23 and the base 29, which is proximal to thetip 23. The distance 82 between the distal end 19 of the expandedproximal portion 21 and the tip 23 of the beveled end 22 of the tube 15is in the range of 1 to 4 inches, preferably about 2½ inches. Thedistance 84 between the distal end 19 of the expanded proximal portion21 and the base 29 of the beveled end 22 of the tube 15 is in the rangeof 9/10 to 3 63/64 inches, preferably about 2 9/20 inches. The distance86 between the base 29 and the tip 23 of the beveled end 22 of the tube15 is in the range of 1/64 to 1/10 of an inch, preferably about 1/20 ofan inch.

Referring now to FIG. 3, in one embodiment according to the invention,the distal end 17 of the tube 15 of the elongated distal portion 27 istrimmed transversely to form the beveled end 22 and its rim 25 is alsochamfered to form a chamfered rim 25. In an alternative embodiment (notshown), the rim 25 of the distal end 17 of the tube 15 is chamfered, butthe distal end 17 of the tube 15 is not also trimmed transversely at anangle from the line 40 (see FIG. 2). Rather, the distal end 17 of thetube 15 is a straight edge cut perpendicular to the long axis of thefront-end loader 12 (i.e., the distal end 17 of the tube 15 is trimmedtransversely so that the distal end 17 is flush with the line 40).Accordingly, in this latter alternative embodiment, the front-end loader12 includes the chamfered rim 25, but it does not also include thebeveled end 22.

Referring now to FIG. 4, in one embodiment, the chamfered rim 25 ischamfered around the entire perimeter of the distal end 17 of the tube15. The chamfered rim 25 includes an outer rim 70 and an inner rim 72.The width 79 of the chamfered rim 25, measured from the inner rim 72 tothe outer rim 70, is in the range of 5/1000 to 30/1000 of an inch,preferably about 15/1000 of an inch. The size of the tube 15 of theelongated distal portion 27 is in the range of 4 French to 15 French.

In one embodiment according to the invention, the width 79 of thechamfered rim 25 is substantially uniform around the entire perimeter ofthe distal end 17 of the tube 15. In another embodiment, the width 79 ofthe chamfered rim 25 is not uniform, but varies, around the perimeter ofthe distal end 17 of the tube 15. In yet another embodiment, the distalend 17 of the tube 15 is chamfered only partly around its perimeter,either in one continuous section or intermittently.

Referring again to FIG. 2, the tube 15 of the elongated distal portion27 may be made from suitable plastic materials (e.g.,polytetrafluoroethylene (PTFE), other polymers and copolymers,polyurethane, polycarbonate, polyethylene, nylon, and polyether blockamides, such as the Pebax® brand sold by Elf Atochem) and/or fromsuitable metals (e.g., stainless steel). In one embodiment, the tube 15of the elongated distal portion 27 may primarily be made from suitableplastic materials, with the distal end 17 of the tube 15 of theelongated distal portion 27 reinforced by metal.

In another aspect, the invention provides a method for introducing andretrieving an implant to and from, respectively, an anatomical site in apatient. The implant, in one embodiment, is the intracardiac occluder200. The invention, for example, is a method for implanting andretrieving the intracardiac occluder 200 destined to occlude a septaldefect, such as, for example, a patent foramen ovale. Briefly, theprocedure involves cannulating the right femoral vein with an 8 Frenchintroducer sheath and then manipulating a 7 French end holeangiocatheter to the right heart. An angiocardiogram may be performed todetermine the anatomy of the septal defect (e.g. the patent foramenovale). An exchange guidewire is then passed through the angiocatheterand the septum is crossed with the guidewire and, optionally, theangiocatheter. With the guidewire placed across the septal defect (e.g.,the patent foramen ovale), the angiocatheter is replaced with theintroducer sheath 150. The introducer sheath 150 is advanced over theguidewire through the right heart so that the distal end 56 of theintroducer sheath 150 lies in the left atrium. To facilitate steeringand manipulation of the assembly, the flexible distal end 56 of theintroducer sheath 150 may be pre-bent to conform to the anatomy withinthe heart. The exchange guidewire, and a dilator if used to predilatethe vascular route, are removed and the introducer sheath 150 is flushedto eliminate air and any clots.

Referring now to FIG. 5, in one embodiment according to the method ofthe invention, the hub 158 of the indwelling introducer sheath 150includes a proximal end 54, a distal end 88, and a gland 90. In theexemplary embodiment shown, the gland 90 is a resilient elastomer andincludes distal portions 91, 93 and proximal portions 95, 97. Beforeintroduction of the front-end loader 12, the distal portions 91, 93 ofthe gland 90 are pressure sealed together by blood 94, which is locateddistal to the distal portions 91, 93 of the gland 90. Air 92 is locatedproximal to the distal portions 91, 93 of the gland 90. The initiallysealed distal portions 91, 93 of the gland 90 prevent the air 92 frompenetrating distally beyond the distal portions 91, 93 of the gland 90and further into the indwelling introducer sheath 150.

Referring now to FIG. 6, in one embodiment according to the method ofthe invention, the distal end 17 of the tube 15 of the front-end loader12 is inserted into the hub 158. As the distal end 17 of the tube 15 isinserted into the hub 158, the beveled end 22 of the tube 15 firstcrosses through the proximal portions 95, 97 of the gland 90. The tip 23of the beveled end 22 of the tube 15 then separates the distal portion91 of the gland 90 from the distal portion 93 of the gland 90 and thebeveled end 22 of the tube 15 crosses through the distal portions 91, 93of the gland 90. As the beveled end 22 of the tube 15 crosses throughthe distal portions 91, 93 of the gland 90, the beveled end 22 permitsthe blood 94 to flow proximally through the gland 90 and, eventually,out of the proximal end 54 of the introducer sheath 150, as indicated byarrow 96. The proximal flow of the blood 94 displaces the air 92proximally and, eventually, displaces, the air 92 from the proximal end54 of the introducer sheath 150, as indicated by arrow 96. As such, theair 92 is prevented from advancing distally beyond the distal portions91, 93 of the gland 90 and further into the introducer sheath 150. Thus,the introduction of the air 92 into the vasculature through theintroducer sheath 150 can be reduced or eliminated. In the absence ofthe beveled end 22 of the tube 15 of the front-end loader 12 (i.e.,where the distal end 17 of the tube 15 is a straight edge cutperpendicular to the long axis of the front-end loader 12, as in theprior art), air 92 might otherwise percolate into the artery into whichthe introducer sheath 150 has been placed and thereby create a risk ofair embolism.

Referring now to FIG. 7, as the front-end loader 12 is advanced furtherinto the introducer sheath 150, the distal portions 91, 93 and proximalportions 95, 97 of the gland 90 seal around the outer surface 78 of thetube 15 of the front-end loader 12, thereby preventing any furtherintroduction of air 92 into the vasculature via the indwellingintroducer sheath 150 and any further proximal flow of blood 94 out ofthe proximal end 54 of the indwelling introducer sheath 150. Once thedistal end 17 of the tube 15 of the front-end loader 12 is positionedbeyond the distal end 88 of the hub 158, the occluder 200, previouslycollapsed, as described above, into a narrow configuration within thesecond lumen 18 of the tube 15, is ready to be introduced, throughactuation of the control assembly 14 (see FIG. 1A), from the secondlumen 18 of the tube 15 into the lumen 152 of the introducer sheath 150.The control assembly 14, located proximal to the front-end loader 12 andoutside of the patient, is advanced by the operator distally into andthrough the first lumen 26 and second lumen 18 of the front-end loader12 to extend the narrowly collapsed occluder 200 from the second lumen18 of the tube 15 into the lumen 152 of the introducer sheath 150.Optionally, the introducer sheath 150 may, at this point, be flushed byinfusing an appropriate solution through a side leg 162 of theintroducer sheath 150. The occluder 200 may then be advanced, by thecontrol assembly 14, throughout the lumen 152 of the indwellingintroducer sheath 150.

In certain circumstances, such as when fluoroscopy or other imagingmethods reveal that the occluder 200 is damaged or too small to seal thedefect under repair, retrieval of the occluder 200 is required. In orderto remove the occluder 200 from the patient with minimal blood loss, theoccluder 200 must be withdrawn from the lumen 152 of the introducersheath 150 into the front-end loader 12. Referring now to FIG. 8A, inone embodiment according to the method of the invention, the occluder200 may be withdrawn from the lumen 152 of the introducer sheath 150into the second lumen 18 of the tube 15 of the front-end loader 12.

Referring to FIG. 8B, by proximally withdrawing the control assembly 14,the occluder 200 is withdrawn proximally into the second lumen 18 of thetube 15 at the distal end 17 of the front-end loader 12. The occluder200 enters the second lumen 18 of the tube 15 by sliding through theopening defined by the chamfered rim 25 at the distal end 17 of the tube15. Because the occluder 200 slides over the smooth slope of thechamfered rim 25 as it enters the second lumen 18 of the tube 15, thechamfered rim 25 eases retrieval of the occluder 200. With the chamferedrim 25 at the distal end 17 of the tube 15, the occluder 200 is muchless likely to catch or snag on the distal end 17 of the tube 15 duringretrieval than it is in the absence of the chamfered rim 25. Theinability to withdraw the occluder 200 into the second lumen 18 of thetube 15 during an attempted retrieval is, therefore, less likely toresult.

Referring now to FIG. 8C, once the occluder 200 is proximally withdrawnpast the base 29 of the beveled end 22 of the tube 15, the front-endloader 12 may be completely withdrawn, through the gland 90 of the hub158, from the introducer sheath 150.

Variations, modifications, and other implementations of what isdescribed herein will occur to those of ordinary skill in the artwithout departing from the spirit and the scope of the invention asclaimed. Accordingly, the invention is to be defined not by thepreceding illustrative description but instead by the spirit and scopeof the following claims.

What is claimed is:
 1. A front-end loader for a percutaneoustransluminal system for an intracardiac device, said front-end loadercomprising: a proximal portion comprising a proximal end, a distal end,and an expanded lumen positioned therebetween, said expanded lumenhaving a conical shape and a constantly tapering diameter from saidproximal end of said proximal portion to said distal end of saidproximal portion; and a distal portion comprising a tube comprising aproximal end, a distal end, a lumen extending therethrough, said lumenof said distal portion being co-extensive with said expanded lumen ofsaid proximal portion; wherein said tube comprises a beveled edge atsaid distal end; and further wherein said tube comprises a chamfered rimaround the entire inner perimeter of said beveled edge, said chamferedrim comprising an outer rim and an inner rim and having a widththerebetween, said inner rim positioned proximal to said outer rim, andwherein said width between said outer rim and said inner rim variesabout the entire perimeter.
 2. The front-end loader of claim 1, whereinsaid intracardiac device comprises an intracardiac occluder.
 3. Thefront-end loader of claim 2, wherein said intracardiac occludercomprises an occluder for treating an atrial septal defect.
 4. Thefront-end loader of claim 2, wherein said intracardiac occludercomprises an intracardiac occluder for treating a ventricular septaldefect